In the electronics industry circuit miniaturization and more compact packaging arrangements have led to the development of different types of connectors for electrically connecting substrates. In general, such connectors may be utilized to provide a detachable electrical connection between adjacent circuit boards. As an example, stacked connectors provide an electrical connection for circuit boards that are stacked relative to one another.
Operationally, a critical aspect of stackable connectors concerns the electrical contact made between the connector and the electrical substrate to which the connector is attached. In greater detail, the connector design must assure that the electrical contact between the connector and the substrate is both correct when established and highly reliable in subsequent use. In practice, however, a number of factors combine to make proper establishment and subsequent reliability of the electrical connection difficult to achieve. These factors include: variations in board thickness, thermal expansion, vibrations associated with various sources, contamination, increasing miniaturization of electronic systems and increasing signal capacities required of connectors.
A second critical aspect of connector design concerns electrical isolation of the electrical components mounted to the substrate. In greater detail, a large number of electrical components may be mounted to a given electrical substrate. Many of these components are themselves conductive to electrical currents. Additionally, the substrate itself often includes a great number of traces each of which is generally conductive to electrical currents. As a result, there is a substantial likelihood of physical contact between either the electrical components mounted on a given substrate or the substrate traces and the electrical connectors used to interconnect adjacent substrates. The likelihood of physical contact increases the chance of unwanted electrical contacts and associated system failures.
To overcome the problems associated with the use of stackable connectors, several connector types have been developed. For instance, one type of stackable connector utilizes a connector body that is placed between adjacent substrates. The substrates are then clamped together holding the connector body in contact with each of the substrates. The chief disadvantage associated with this connector type is the need for a separate clamping mechanism and the resulting need that the clamping mechanism be specially configured to provide the tolerances required to maintain proper contact between the connector and the respective substrates.
Another connector type positions a connector body between two substrates and then attaches each substrate to the connector body. This connector type functions as both an electrical connector and a means of physically attaching and positioning adjacent substrates. Connectors of this type typically provide screws or bolts which pass through the substrate and attach the connector. U.S. Pat. No. 4,057,311 which issued to Evans for an invention entitled "Elastomeric Connector for Parallel Circuit Boards" and U.S. Pat. No. 3,551,750 which issued to Sterling for an invention entitled "Circuit Board Connector" disclose prior art connectors which function both as electrical connectors and a means of physically attaching and positioning adjacent substrates.
The Evans and Sterling inventions, however, included several impediments. Specifically, both inventions relied on the use of separate clamping bolts passing through the connector and the adjacent substrates. These bolts, if conductive, require that electrical components or board traces be eliminated from the areas in which the bolts make contact with the substrates. Additionally, the bolts are separate pieces making the bolt and connector assembly more costly to manufacture and install and increasing the likelihood of defects introduced at assembly time. Finally, the bolts require the use of specialized tools as the substrates are assembled further increasing the cost and difficulty associated with the use of these connectors.
The present invention recognizes the need for an inexpensive single-piece stackable connector for adjacent circuit boards. Furthermore, the present invention recognizes the need for a connector with associated mounting hardware that is non-conductive and does not interfere with electrical traces present in printed circuit boards.
In light of the above, it is an object of the present invention to provide a low-cost stackable connector for adjacent circuit boards that features single-piece construction. It is yet another object of the present invention to provide a low-cost stackable connector for adjacent circuit boards that will not interfere with electrical traces present in printed circuit boards and may be assembled by hand without the need for specialized tools. Still another object of the present invention is to provide a low-cost stackable connector for adjacent circuit boards which is simple to use, relatively easy to manufacture, and comparatively cost effective.